The objective of this project is to investigate, in a systematic, multilevel series, the organic and acoustic components in the etiology of the voice disorder "spastic dysphonia". The experimental data obtained from exhaustive laryngoscopic, phoniatric, electromyographic and histologic examinations will be coordinated, cross-correlated and compared with normative data. This will be done to determine the possible etiology, genesis and site of lesion, as well as documenting in detail the characteristics of patients with this disorder. Experimental animals will be used to study the relevant neural topography of the recurrent laryngeal nerve and the neutral control of the larynx. Standard electrophysiological and neuroanatomical techniques will be employed in these studies. In later stages, this voice pathology will be modeled in animals. Relevant human data will be used for computer modelling of deviant vocal fold function. Ultimately, the results will be applied for better diagnosis, management and treatment of spastic dysphonia and other communicative disorders.